wc -l medals.txt
grep -E '^(中国|中国香港|中国台北)' medals.txt | sort -t',' -k2 -nr
sort -t',' -k4 -nr medals.txt | head -n 5 | cut -d',' -f1
sort -t',' -k2 -nr medals.txt | head -n 5 | awk -F',' '{sum += $2} END {print sum}'
